Sony's Reon wearable air conditioner saved my sanity through multiple heatwaves

Earlier this month, temperatures where I live in London hit 100.6 Fahrenheit. It was the country's hottest day of the year, and part of the third heatwave of an oppressive summer. I am not built for this. The UK is not built for this. Air conditioning remains a rarity outside shops and offices: Research from the University of Reading estimated that there's A/C in just 4.3 percent of English homes – compared with 90 percent of US homes. The trains I commute on don't have it either, nor do many bars, restaurants and other places I visit often. As the second heatwave struck, I was willing to do anything for some relief.

Sony has experimented with wearable air-conditioning tech for years, but for most of that time the Reon Pocket series was a curiosity. They were difficult to find, and performance was middling. The company kept improving how much cooling the device can deliver, while making it more comfortable, less obtrusive and more power efficient. The $260 Reon Pocket Pro Plus is the series' latest model.

The main thing is that it's surprisingly effective at cooling your body down. The device uses the Peltier effect: A long, electrically cooled metal plate sits against the back of your neck and the top of your spine. That positioning is the whole trick. So much of your circulatory system passes through that area that the Reon effectively becomes a cooling station for your blood flow.

With the Pro Plus, Sony says it can drop the plate an additional two degrees Celsius (3.6 Fahrenheit) over the previous model — a 20 percent jump in cooling performance in a single generation. Hot air is propelled up and outward through an exhaust that peeks over the neckline of your clothing. The Pro Plus ships with an attachment that extends the exhaust further and lets you adjust its angle, which was essential for me with anything that had a collar or a thick hem — shirts, jackets and structured necklines. If you're just wearing a tee, you can use the shorter vent. While you can hear the fans whir in a quiet room, the device is remarkably quiet, especially compared to many handheld electric fans.

Sony's built-in algorithms monitor temperature changes on the device and in the surrounding area. The Pro Plus includes a smart tag you can clip to your bag that adds another data point by tracking ambient temperature and humidity. In practice, the tag was useful at times but unreliable at others. It unpaired easily, the reconnect button is finicky and it's only as effective as you are at remembering to take it with you; I regularly grabbed a different bag (or no bag at all) and left the tag at home. Honestly, I couldn't detect a tangible difference in cooling when it was around. The Reon Pro Plus performed just as efficiently without it. Outside of these summer months, the Pro Plus also has a four-level warm mode for winter, but I haven't tested those yet. Obviously.

Sony says the Pro Plus can cool for up to 10 hours on its second-highest manual setting, or up to 15 hours in Smart Cool mode, where it adjusts output based on its sensors. As with any cooling product, mileage will vary widely depending on context and environment. During peak heatwave days — and World Cup matches in pubs without air conditioning — I got closer to four or five hours. I'd assumed I wouldn't be able to charge it while wearing it, but you can, if you're willing to have a USB-C cable billowing out of the bottom of your clothes.

Mat Smith for Engadget

A real upgrade is the physical buttons on the device itself. You can do almost everything the companion app offers without your phone: power, switching between manual and smart modes and adjusting the cooling up or down. Sony says the Y-frame neckband that holds it in place has 40 percent more securing force compared to older models. I haven't used the immediately previous iteration — I tried a very early version of this tech years ago — but it stays put surprisingly well.

However, it could be subtler. Under a jacket or blazer, or anything more structured, the silhouette smooths out. But I mostly wear slouchier shirts and tees, and in those it looks like a robot bug has been glued to your neck. People will notice. People noticed. A few assumed it was a medical device — and it certainly looks like one. The combination of a cold surface and a hot body also generates a fair amount of condensation underneath your top, although I'd still take that over sweating. Thankfully, the Pro Plus is splash- and sweat-resistant.

Nothing else really does what Sony's Reon devices do, effectively. Shark's $150 ChillPill is the closest thing, and it's a smarter take on the handheld fan than most, bundling a cooling plate and a Dry Touch mister alongside the fan mechanism.

But misting fans are fussy and largely futile on a packed commuter train, and can be completely ineffective during high humidity. You also have to hold the thing, or prop it up somehow. That's one benefit of the Reon I didn't appreciate until weeks in: it's entirely hands-free.